Client’s see WINMAIL.DAT attachments in Thunderbird but in Outlook they open fine

Dynamic sends invoices and statements to clients’ by email.  This is a great time saving feature but sometimes problems occur.

One such problem is the display of the attached PDF in Thunderbird.

What is this?

This not a Dynamic issue.  The issue is experienced by Thunderbird users who received PDF invoices sent by Dynamic.

The problem is with Thunderbird.

Any PDF sent as an attachment will be treated in this way by Thunderbird.

Who gets this?

The problem described here is typical for Thunderbird users and the same email, with attachment, forwarded to an Outlook user will not report the same problem.

Why is this important?

Never open untrusted attachments.

Clients may complain that they do no receive invoices sent to them by email.

The attachment is normally named invoice_123456789.pdf – and in standard PDF format.

Thunderbird users may report that they do not see a PDF attachment.  The attachment may appear as a winmail.dat attachment.

Solution

The solution lies with Thunderbird.  Please install the LookOut plugin for Thunderbird.

Download LookOut for Thunderbird

Never open untrusted attachments.

Additional information for this issue:

From Mozilla Help for Thunderbird:

When people send messages from incorrectly configured Microsoft Outlook email clients, a file attachment called winmail.dat may be added as an attachment to the message. This file contains formatting information for messages that use Microsoft’s proprietary TNEF standard and any attachments sent with the original message. The file is not recognized by other email clients. Because of this, any attachments sent with the original message are not displayed in Thunderbird’s message pane.

-Dynamic